Based on the adaptive antenna principle, beam-forming performs weighting process for each antenna unit respectively using antenna arrays through the advanced signal processing algorithm, so as to make the antenna array aim at the direction of a useful signal in real time and form a zero point in the interference direction to suppress the interference signal, thereby improving the signal noise ratio (SNR), enhancing the system performance and expanding the system coverage area. FIG. 1 shows a diagram of a beam-forming system based on linear antenna array according to the relevant technology.
Multiple-input multiple-output (MIMO) is a communication system which arranges a plurality of antennas at the transmission end and the receiving end respectively and can improve the stability of link or increase the throughput of system without increasing bandwidth resources. The combination of MIMO with beam-forming forms a new technology which has advantages of both MIMO and beam-forming, that is, MIMO beam-forming which is abbreviated as MIMO+BF; the MIMO+BF not only has advantages of interference signal suppression of beam-forming, but also has advantages of link reliability or transmission rate enhancement of MIMO.
MIMO beam-forming generally has two implementation schemes. FIG. 2a shows a first diagram of a method for realizing MIMO beam-forming according to the relevant technology; the entire antenna array has M antennas which are divided into N sub-arrays, wherein each sub-array forms a beam, thus there are N beams totally; the N beams form an MIMO system of which the weight is an M×N dimensional matrix, wherein the ith column of elements is the weight of the ith sub-array; for the elements in the matrix, except that the antenna corresponding to the ith array has a non-zero value, the value of others is 0; for example, four antennas are divided into two groups evenly, the weight is
      W    =                  (                                                                              w                  11                                ,                                  w                  12                                ,                0.0                                                                                        0.0                ,                                  w                  13                                ,                                  w                  14                                                                    )            T        ,the weight also can be represented as a vector W=(w11, w12, w13, w14)T, wherein the two expressions are equivalent. FIG. 2b shows a second diagram of a method for realizing MIMO beam-forming according to the relevant technology; the entire antenna array has M antennas, wherein the M antennas have N beams, an MIMO system is formed among the beams and the weight of the MIMO system is an M×N dimensional matrix. In the application, the weight of the MIMO beam-forming is uniformly defined as an M×N dimensional matrix, which is marked as W. The transmission end called in the application is a device used for transmitting data or information, for example, macro base, micro base, etc.; the user called in the application is various terminals used for receiving data or information, for example, mobile station, handset, data cart, etc.
In the relevant technology of MIMO beam-forming, some factors would restrict the system to make full use of time frequency resources, thus the throughput of system is reduced; for example, in the partially used sub-channel (PUSC) frame structure of the worldwide interoperability for microwave access (Wimax) 16e protocol, the downlink sub-channel with 10M bandwidth is divided into 6 groups. FIG. 8 shows a diagram of group resources according to the relevant technology, in which, the odd-number group includes 6 sub-channels and the even-number group includes 4 sub-channels. Since the resource applies distributed mapping and uses a dedicated pilot frequency, each group resource can only use one beam-forming weight for data beam-forming, however, the beam-forming weights of different users are different; therefore, each user needs to be allocated with at least one group of sub-channels while the downlink sub-channel with 10M bandwidth is divided into 6 groups; therefore, there are at most 6 users having a scheduling chalice at the same moment, thus the number of accessible users is limited; besides, if some users only need a few sub-channel resources (for example, one sub-channel resource), the resources remained in the odd-number group or even-number group are wasted.